The proposed research seeks to illuminate the mechanisms responsible for association in episodic memory-the form of memory that shows the first signs of impairment in normal aging and neurodegenerative disease. In particular, these studies will both test predictions of, and further generalize, the Temporal Context Model (TCM), a mathematical model of recency and association in episodic memory. This model precisely characterizes the mechanism of contextual coding, contextual drift, and associations between items and context. Twelve proposed experiments were designed to achieve four specific aims. The first aim is to determine the temporal domain over which associative processes in episodic retrieval are scale invariant. Aim # 2 is to test the hypothesis that contextual retrieval is the principal cause of associative effects in free recall, and that dissociations in the serial position curve reflect dissociations between cueing with end-of-list context and cueing with retrieved context. Aim # 3 is to test the hypothesis that free and serial recall share a common associative basis. Using self-initiated recall of lists varying in temporal and positional structure, our last aim is to test the contextual retrieval/compound cueing hypothesis of episodic association. Addressing these basic scientific questions about episodic memory will provide us with important insights into the mechanisms of memory decline both in normal aging and in neurological disease.